Optical disks are an increasingly popular medium for digitally storing information. Information is stored in binary format, with binary zeros represented by non-reflective pits stamped into a plastic disk and binary ones represented by reflective high points on the disk. The data is retrieved by an optical head which directs a laser source onto the surface of the disk and which utilizes a light sensitive photo diode to detect light reflecting from the disk surface. The binary information is converted to electrical signals and decoded into audio and/or video output.
In present large-scale optical disk storage and retrieval systems each disk is installed in a separate cartridge having a separate drive. Each drive is comprised of an enclosed casing which includes the disk and all of the components, including the interface, loading and unloading mechanics, drive mechanics, optical head, and all of electronics which are necessary for retrieving the data from the disk and delivering the data to the host computer. The drives installed in the storage system are multiplexed to the central processing unit.
These extensive storage systems are highly desirable because of their large capacity and because they provide immediate access to data stored on any of the installed disks. However, these storage systems require considerable amounts of bulky hardware and therefore are extremely costly and highly consumptive of space and power. This makes them impractical for use in schools, small libraries and other small businesses.